1. Field of the Invention
This invention relates to a heat-resistant resin composition. More particularly, this invention relates to a heat-resistant resin composition excelling in formability as in terms of curability and workability, permitting production of a cured article satisfactory in stability even at elevated temperatures and in mechanical strength, and defying the occurrence of cracks due to thermal expansion and shrinkage during the course of curing.
2. Description of the Prior Art
As resins possessing high stability at elevated temperatures, various heat-resistant resins are cited which are represented by polyimide resins and polyamideimide resins. These heat-resistant resins, however, have important problems regarding formability as because they have high melting points and, therefore, necessitate use of a high temperature and a high pressure for molding, because they require to stand at a high temperature under a high pressure for a long time for curing, and because they require to be used as dissolved in special high-boiling solvents and, therefore, entail a step for the removal of the solvents by a protracted standing at an elevated temperature under application of pressure or under a vacuum. It is, therefore, extremely difficult to produce large formed articles from these heat-resistant resins or to produce formed articles of these resins continuously as by pultrusion molding or extrusion molding.
As resins excelling in formability in terms of curability, workability, etc., radical polymerization type resins such as epoxy (meth)acrylates derived from polyvalent phenol type epoxy resins such as bisphenol type epoxy resins or novolak type epoxy resins and (meth)acrylic acid or unsaturated polyesters have been known in the art. Generally, these resins are widely used in the form of vinyl ester resins or unsaturated polyester resins having incorporated therein a radically polymerizable crosslinking agent such as styrene. These resins, however, are not necessarily quite satisfactory in terms of thermal stability at elevated temperatures. This deficiency in thermal stability constitutes a serious hindrance to the development of applications for the resins. In the circumstances, the desirability of developing a resin excellent in thermal stability has been commanding the recognition of the industry.
An object of this invention, therefore, is to provide a novel heat-resistant resin composition.
Another object of this invention is to provide a heat-resistant resin composition excelling in formability as in terms of curability and workability, permitting production of a cured article satisfactory in stability at elevated temperatures and in mechanical strength, and defying the cccurrence of cracks due to thermal expansion and shrinkage during the course of curing.